1. Field of the Invention
The invention pertains to loom shuttles and more particularly to a stabilizing member disposed in operative association with the spring gripping element for releasably holding a weft bobbin within a shuttle. The stabilizing member is effective in locating the opposed gripping surfaces of the gripping element in a position that will provide consistant uniformity of each bobbin transfer and which will be accomplished with less force than has been heretofore required.
2. Description of the Prior Art
Loom shuttles of the type to which the present invention is applicable include an elongated shuttle body with a cavity therein for receiving a weft bobbin. A shuttle spring having opposed jaw members and a U-shaped shank portion is assembled in the shuttle body in a well known manner so as to releasably hold a weft bobbin in the cavity of the shuttle. The type of shuttle spring with which the stabilizer of the present invention is adapted to be operatively associated during the performance of its intended function is shown and described in U.S. Pat. No. 2,729,247.
As is well known to those conversant in the art of fly-shuttle weaving, the opposed jaw members of a shuttle spring must be spaced so as to provide a gripping force on the butt portion of a bobbin which will firmly hold the latter against displacement within the shuttle's cavity as the shuttle is picked back and forth across the width of a loom. To provide an adequate gripping force on the butt portion of a bobbin, the opposed jaw members in their relaxed position have a distance therebetween which is considerably less than the diameter of the bobbin rings which are carried on the butt of the bobbin and which are adapted to be engaged by said jaws to firmly position the bobbin in the shuttle cavity.
The opposed jaw members of a shuttle spring are subjected to what is considered excessive lateral movement or flexing during bobbin transfer which in a known manner is effective in replacing the spent bobbin in the shuttle cavity with one having a full yarn package thereon.
At transfer, the initial movement of a fresh bobbin toward the shuttle causes the butt portion of said bobbin to engage and flex the opposed jaws outwardly beyond their normal bobbin butt gripping position. The spent bobbin is engaged and forced out of the shuttle cavity by the incoming bobbin and during the interim period before the latter bobbin is in position to be held by the opposed jaws, the biasing force of said jaws causes them to flex inwardly beyond their free position and thence immediately outward. High frequency vibrations are set up within the opposed jaws during this interim period and tests have proven that said jaws can move more than once in this manner before the incoming bobbin is in position to be gripped and firmly held by the jaws.
This excessive lateral movement or flexing of the opposed jaw members during bobbin transfer in combination with the amount of force required to move or spread said jaw members a sufficient distance for the reception of a new bobbin has been responsible for a number of serious conditions which require frequent attention as well as what is considered an excessive amount of time to correct such conditions. The impact of the steel bobbin rings striking the spring steel jaws of the shuttle spring has been responsible for wear developing in both the bobbin rings and the steel jaws as well as breakage of said shuttle spring. Additionally, improper bobbin transfer will frequently occur should the gap between a bobbin ring become aligned with the upper edge of one of the jaw members so as to cause a collision between these elements at transfer. Such a collision will seriously damage or break both the bobbin and shuttle spring. Shuttle spring breakage is also attributed to the lateral flexing movement of jaw members during transfer which induces fatigue failure of said jaw members.
U.S. Pat. No. 2,154,050 shows and describes a means for damping the vibrations that develop in the opposed jaws of a shuttle spring. This means comprises a resilient block interposed between and in engagement with the opposed jaw members. Although this device provides a means to cushion or dampen movement of the opposed jaws toward each other, the problems still exist which are associated with flexing relative to fatigue failure of the jaws as well as the amount of initial force required to transfer a full bobbin into the shuttle cavity.
The shuttle spring stabilizer according to the present invention provides a very definite advance in the art by substantially reducing the above-described problems associated with bobbin replenishment in fly-shuttle looms. The stabilizer is carried within the shuttle spring and is effective in limiting the inward movement of the opposed jaw members after the removal of a spent bobbin that was held therebetween. Additionally, the jaw members are maintained in an outwardly flexed predetermined position by the stabilizer which reduces the distance the jaw members have to be opened or spread to receive a fresh bobbin.
As is well known to those conversant in the art, the opposed jaws of shuttle springs are provided with grooves which are adapted to receive and grip the rings of a bobbin. The upper surfaces of the jaws adjacent these grooves are tapered downwardly a distance to communicate with said grooves and provide camming surfaces that are engaged by a bobbins's rings during transfer to effect the spreading of said jaws a distance sufficient for the bobbin rings to enter the grooves. By maintaining the jaw members in an outwardly flexed predetermined position less camming force is required to transfer a fresh bobbin into the shuttle cavity and prevents inward flexing of the jaw members during transfers thus promoting longer spring life by eliminating the high frequency vibrations referred to above.
With the jaws always being in the same location to receive a fresh bobbin will provide a more uniform and consistant transfer condition for each new bobbin than has heretofore been possible and the greater space between the opposed jaws will reduce substantially shuttle spring abuse caused by the bobbin rings at transfer and will minimize the possibility of the gap in a bobbin ring becoming engaged with the upper edge of a jaw member.